At 2:04pm, the University of Michigan Department of Safety and Security’s (DPSS) Twitter posted this tweet:

UM EAlert Ann Arbor: Active shooter in Mason Hall . Run, hide, fight. https://t.co/w9rEgQfZYw.

— U-M DPSS (@umichdpss) March 16, 2019

Mason Hall, on State Street, was immediately locked down. Photos of people trapped in the building started to surface online, with furniture pushed up against doors to prevent a potential break-in.

A photo sent to The Daily from a student in a university library: pic.twitter.com/oTgnPdvouw

— The Michigan Daily (@michigandaily) March 16, 2019

The alarm had been called due to ten 911 calls reporting loud popping sounds that resembled gunshots nearby Mason Hall, followed by a group of University of Michigan students running and screaming away from the sound’s area of origin.

Nearby, a vigil was being held for the victims of the New Zealand mosque shootings. Upon hearing the sound of gunshots, the crowd fled the scene, seeing a possible connection between the sound and the memorial of those killed by gunfire.

By 7:50pm, DPSS, aided by police officers from across the county and even the FBI,  had cleared the campus of students and faculty.

Police reported that there were no active shooters in the area; the sound of gunshots was related to a group of University of Michigan students popping balloons nearby Mason Hall. A group of civilians supposedly mistook it for the sound of gunfire and screamed, fleeing the scene.

The initial alert received criticism for using Twitter as a means to notify people of an active shooter, as opposed to a text alert sent directly to students and faculty member’s phones.
(

A little late!!!!! And why didn’t you push a notification via your App????? Had to go on to see alert. Not happy with your response.

— Suzie Canes (@1MiamiHurricane) March 16, 2019

)DPSS released a statement a day after the event, thanking those involved for their cooperation and offering counseling for those in need of support.